Spar Urethane .. white looking? How long to turn clear?

lorriekayNovember 15, 2010

I am a super duper novice, first time doing this

I applied diluted Helmsman satin Spar urethane, diluted 50 percent with paint thinner for First coat on hardwood table. I applied it with a rag and plan to sand between coats with many coats. Less and less diluted for first coats and then last coat not diluted.

It seemed to go on clear. I just put a thin layer.

I just checked it and the whole table looks a chalky white. Almost like bleached white wood now.

It has been 1 hr and 15 minutes since I finished applying the first coat. It is outside in open air. Not humid. not hot, moderate weather.

Is this normal? I have searched on the internet and cannot tell if it is supposed to turn white like this.

- It is not more moisture resistant, it is less
- It is not more durable, it is softer and more prone to things like pen impressions.

The major attribute of a spar (long-oil) varnish is its ability to remain soft and flexible. That's an advantage on a boat, a disadvantage on furniture.

But by using a urethane resin, it is much less UV resistant than a non-urethane spar (marine) varnish. In a sun-rich environment, you can expect to last only months before it starts to break down.

If you really have a proper application for spar varnish, expect to pay about $40 a quart for it. Even then you will need regular (annually or bi-annually) maintenance on it.

It's hard to diagnose your problem by reading your description. Though your process of wipe on many thin and thinned coats is a good approach for a varnish.

One possible cause is the flatteners (silica) that create a lower-sheen finish. If you don't stir extremely well both before and after thinning and frequently during application, you can end up with cloudy finish because it has too much flattener in it.

First, advice from the greater majority of Lowe's/Home Depot/Menards aprons is the last advice I would take. How do I know? I was a small contractor for several years and seldom got anywhere close to the correct advice when I tested their knowledge.

You want painting/finishing advice, go to a paint store or a woodworking store. Or find an online subject specific forum or get a book on the subject.

You probably caused the problem by thinning the spar varnish.

The wiping part was a good idea, you just used the wrong product.

If you still have the cloudy finish, you will probably have to strip or sand it off---stripping being the safest(for the wood) choice.

Then go to a paint store(I prefer Sherwin Williams) and get a fresh can of varnish and see if they recommend the best way in which to wipe it on to apply.

I can't tell you how many horror stories I've heard that begin, "The guy at [big box home center] said to..." They usually end with, "... How do I fix this?"

While some of them know paint, few of them I've run into know diddly squat about wood finishes. I even went into a nationally known paint store once and asked if they had a can of shellac.
"Shellac based primer??"
"No, just shellac."
"I don't think we have that." Minutes later, "What do you use shellac for?"

And the drone at Wal*mart, when asked, "Do you have gallons of acetone?"
"Acetone? (acetone?) Um, what do you use that for?"
"I use it to clean up when I'm stripping finishes."
"Oh, the strippers are over here."
(sigh). "OK, where are your cans of paint thinner, then"
(pointing)"Over there."

Typical phone conversation at my local independent paint store:
"Hey Patrick, this is [my first name]. I need a gallon of oil-based glaze."
"Hi, [my first name], what color?"
"Van Dyke Brown."
"X-Brand or Y-brand?"
"X-Brand."
"OK, we'll have to mix it up. It will be ready by noon."

>First, advice from the greater majority of Lowe's/Home Depot/Menards aprons is the last advice I would take. How do I know?

If you were trying to reduce your urethane with mineral spirits, and I'm glad you got a nice look, but you need to look at the side of your can and see what is in urethane. MEK (methyl ethyl ketone) is a part of it and also what can break it down. So many people just grab a solvent that is in reach and assume that will do the trick (min. spirits, lacquer thinner), and end up with unhappy results.

I suspect that since the OP said it was a "refinishing job" that she had shellac on the table originally, and the wax in the shellac created the white discoloration. That's what happens if there is wax under poly, an instantaneous white bloom. The only cure it to refinish, strip the poly and correct for the wax (technically "stearates") .
4 yrs. old thread anyway, so nobody cares.
Casey